I have a 1995 Chevy C1500. I'm converting from TBI to old school carburetor. I'm having an issue with the conversion. Can you help me or know someone who can? Thank you in advance.
Im not real sure, i do know that just in the v8 version there are different computers and different harnesses and you cant mix and match. Like the wiring and computer are different from a 94 model to a 90 model and will have a completely different pinnout.. so if you were to stick a 90 model computer into a 94 harness it wont work...so it just depends. Best thing i can tell you is to look uo your ecm number and find the pinnout data for that specifically, then youll have to check all the wires in your harness and make sure it matches up to the ecm.. if not you may have to change pin locations or add and subtract wires to make it right.
M.A.C. Works you can find everything online. Google tbi pinout, and you will find information. You will have to search for the specifics year of ecm that you are working with because there are different ones and they use different wiring diagrams.
Erocks Garage thank you. I am actually trying to do the opposite and need to remove the stock engine harness for my LS engine wiring to replace it. Need to keep transmission sensors, ac control, starter wires, brake controls, etc
M.A.C. Works ah that makes sense. Your best bet is to unwrap the harness that goes inside the cab to the computer. Pull it out of the firewall and unwrap it all. You can remove all of that, everything that goes from the ecm to the engine. All of the other controls will come from the fuse block on the driver side firewall. You are going to have to just dive in there and remove the tbi harness manually. Take the loom all apart and remove it. The harnesses are integrated but most of it goes directly from the ecm to the engine. Dissect it and cut it out.
I'm in the process of pulling a 305 TBI out of a 91 Caprice and trying to simplify the harness to run the engine. I was having a hard time finding any schematics online, but ill try the pinout on google.
I believe I found the pinout data I needed after searching my ecm number. Thanks for your help. Going to try and run it on a stand in the next couple days after I get the harness simplified.
So I've got the wiring broke down and hooked up on the stand. The does its initial prime and then shuts off, but when I go to crank it doesn't start spraying. Isn't there an oil pressure switch that controls when the injectors start spraying? Thanks
Any tricks to removing the sealant and plastic connector where the harness passes through the firewall? I have the harness out but the harden gel is a pain to get off! Thanks
It is a pain to get the wires out of there!! It took me a while, I just carefully peeled each wire out individually. Once you get the plastic cut open and wittle down the Silicon crap. It was a slow process, but probably didn't take me more than 30 minutes or an hour. Just gotta sit down and do it. Grab a beer and put some tunes on man
Hi Ed, its not something i would do for hire. You be better off ordering a harness from painless or somebody who makes those. Thanks for watching brother
P Bond, nope not at all. These early years did not have vats (anti theft), so there is not really anything to reprogram, if you keep it stock. On both jeeps I did, I used the stock computer and chip, and they both work fine.
P Bond, it worked out great. I have actually done this a couple of different times in different vehicles. Super reliable, and starts everytime! I have a few videos of a blue jeep on my channel, the harness in this video is in the blue jeep now. Also the black jeep on my channel has the same setup a tbi 350 with a stock harness stripped down. ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-8axlZH1kmfM.html
have the wiring in the jeep, left the oil pressure plug off due to wanting a manual gauge instead. Jeep will start if i put fuel into the throttle body....I have a fuel pump on a separate circuit, not tied into computer. I tested and found no pulse for the injectors. Do i need to wire in the oil pressure switch?
P Bond, I do not have any of the stock gm oil pressure wiring in my setup. I took the wiring for that, out of the harness. I used a jeep oil pressure sending unit, which only has one wire which goes to the dash to work the gauge.. There is a main hot, for the injectors that has to be run. Did you follow the schematics closely? Also you should have the fuel pump controlled by the computer. The computer should turn the pump off and on.
P Bond, it seems like something does loop thru the oil pressure wiring, although I couldn't tell you what, with it looking at your wiring diagram. Probably something with the fuel pump wiring I think. Like I said, I took all that out of my harness so if something was looped then I would have repaired that or taken the loop out. Look up the wiring diagram for your ecm. What is your ecm number?
P Bond, I did some digging and indeed the fuel pump wiring loops thru the oil pressure switch, it's a saftey so if it looses oil pressure, theoretically it should turn off the fuel pump to stop the engine. Like I said, I did away with that part in my harness. My wiring goes straight from the fuel pump relay directly to the pump, and has a leg that splits off and goes to the ecm to tell the ecm if the pump is running or not. The keyed ignition hot for the fuel pump relay also runs thru the oil pressure switch, so in my system I would have removed that, and ran my keyed hot straight to the fuel pump relay. Then there is one other wire from the ecm that tells the relay to turn the pump on and off. It would be easier to show you on a diagram. Kinda hard to explain. Look up the wiring diagram for the vehicle it came from and one specific to your ecm number because different years had different diagrams and wire routing. Hope that helps. Also don't forget the keyed hot to the injectors too! They gotta have power! You will have keyed hot to several things, injectors, ignition, fuel pump relay, etc.
